The servlet has a ServletConfig object, a method that four config objects can call, a ServletContext object to get Web project information, and a configuration that sets the global initialization parameters __web

ServletConfig objects

each servlet has a ServletConfig object

ServletConfig The object used to obtain the related configuration of the servlet.

get ServletConfig object: Direct This.getservletconfig () To return config object directly

the method that four config objects can call:

 

Getinitparameter (String name); Gets the value of the parameter initialization by initializing the name

Getinitparameternames (); By this method, returns an enumeration of String generics, enumeration<string>; Inside is the name of all the initialization. Gets all of the corresponding values through traversal.

With the enumeration object. Call the hasMoreElements () method to know if there is a next element. Nextelement (); get the next element

Getservletcontext (); Get ServletContext object

getservletname (); Get the name of the configuration

Configure initialization parameters

Configure the name of the initialization parameter in the label <init-param> configuration and the corresponding value <param-name> and <param-value>

5 ServletContext object to get Web project information

Overview of ServletContext objects

What is ServletContext

The context object for the Servletcontext:servlet. The ServletContext object is known to the content before and after the servlet. This object has only one Web project . Create a separate ServletContext object for each Web project when the server is started.

The role of ServletContext objects

Function one: To get Web project information

because a Web project has only one ServletContext object, This object is known to be relevant to the entire project.

Method:

gets the object of the ServletContext returned by the ServletContext object through the This.getservletcontext ();

gets the MIME type of the file: GetMimeType (filename);

gets the project name of the Web project request: Getcontextpath ();

To set the configuration of global initialization parameters: Add <context-param> tags to web.xml and add <param-name> and <param-value> values to this tab

gets the initialization parameter in the Web project XML file: Getinitparameter ("parameter name") returns the value of the parameter

gets the full name parameter name of the file for the Web project xml: Getinitparameternames (), returns an enumeration of string generics, enumeration<string>; inside is the name of all initialization. Gets all of the corresponding values through traversal.